We have recently discovered that ultrasound can enhance the degradation of solid polymers and the transport of incorporated substances within polymers, as well as the transport of drugs through the skin. The effects appear to be reversible and occur with respect to a variety of polymers and drugs. For example, enhanced release rates of drugs (up to 20 fold) via ultrasound have been observed with biodegradable polyanhydrides and polyesters, with non-degradable ethylene-vinyl acetate copolymer and with skin. The effect has been observed with seven different releasing agents - all that have been tested. Finally the effects have been observed both in vitro and in vivo(1,2). We now propose to study this phenomenon in depth. In particular, we propose to conduct in vitro studies examining the effect of polymer physical and chemical properties, effect of incorporated agents, effect of polymer processing characteristics and finally effects of ultrasound characteristics. We also propose in vivo studies examining the physiological effects of ultrasound, and effects of ultrasound on polymer degradation and drug release.